Clojure noob, here. I'm very excited to be learning about this language and becoming a part of this community :) I'm writing a function that works well, but seems just a bit wrong to me, stylistically speaking. I was hoping I could get some guidance from you all.
Here's the code: (defn get-if "Gets the value of a map if exactly one key matches a predicate, otherwise nil" ([m predicate?] (get-if nil m predicate?)) ([found m predicate?] (if-let [e (first m)] (let [pred (predicate? (key e))] (if (not (and pred found)) (recur (if pred (val e) found) (rest m) predicate?)) found)))) This has gone through a few revisions to get it as concise as possible, but here are my questions/remarks: 1. Is it idiomatic to use if-let to move through a collection the way I have? In my experience with lispy languages, recursion over sequences tend to take the form (if (null item) accumlated-value (recur-over-rest)). This if-let form turns that on its head, which looks a little backwards at first to me, but it saves a level of indentation which is generally preferable in my experience. 2. The main part of this code that's bugging me is the let form, which is a total hack to keep from testing (predicate? (key e)) twice. Even still, I have to test the truthiness of pred twice; once in the (not (and ...)) form and once again in the if of the recur form. I feel like a clever use of (and ...) or (or ...) would save me here, but I haven't come upon a solution using those forms yet. 3. In general, when using recursion and multiple arities to get a result, is there an order that is preferred for the extra recursion accumulation values? Here I have [m predicate?] and [found m predicate?] versions of the function, but after looking at it for so long I think it might be more natural to put found as the last argument, as in [m predicate? found], but I'm wondering if there's a standard to follow with things like this. 4. When passing functions as arguments, as I have here with the predicate? function, is there a standard naming convention? I used a question mark here, but would predicate be preferable, or even simply f? 5. Is writing this function even necessary? I didn't see a function that serves the same purpose in the standard libraries, but I'm very new and could easily have missed something! I know that's a lot to ask for such a short segment of code. Feel free to answer as many/few of these questions as you'd like, as any help would be greatly appreciated (though, if you're going to answer one, I think point #2 is the most important) :) Thanks in advance, fellow clojurians! -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.